bush said to be improving even though he remains in intensive care at a hospital in houston. a bush family spokesman says the 88-year-old is alert and in good spirits. the doctors are cautiously optimistic. mr. bush was hospitalized for a bronchitis-like cough more than a month ago. we have asked dr. kim mulvihill to fill us in. what's guarded? >> reporter: that means he is between stable and critical. he will be watched closely. bronchitis can take months to clear but anytime the elderly have bronchitis it could develop into a more complicated lung infection pneumonia especially when the patient is in the icu. >> the difference between bronchitis and pneumonia? >> bronchitis is an inflammation of the large airways that carry air from the mouth to the lungs. pneumonia is an infection of the lung tissue itself. this infection inflames the air sack and they film up with fluid and can cause symptoms such as a cough with phlegm, fever, chills and trouble breathing. >> and pneumonia is treatable, right? >> absolutely. it usually is. most adults it will take a week or two to clear.